Abstract

Analysis of January and February 1979 Scanning Multichannel Microwave Radiometer (SMMR) data has revealed discrepancies in the responses of vertically and horizontally polarized brightness temperature (TB) data to snow in the state of Indiana. Ten satellite overpasses were analyzed between January 8 and February 21, 1979. In four cases, the horizontally polarized TBs correlated with snow depth significantly better than did the vertically polarized TBs. These four overpasses occurred either when the snowpack was building up or when it had metamorphosed and/or was melting. For example, on February 17, the coefficient of correlation, R, between vertically polarized TB and snow depth was R = -.46 while it was R = -.86 for the horizontally polarizedTB data. Just prior to February 17, air temperatures rose above 0°C in the study area causing melting of the snowpack. On February 17, air temperatures dropped well below 0°C and the snow and water in the snowpack froze causing a metamorphosis of the snowpack. It is concluded that horizontally polarized TB data may be more useful than vertically polarized data for analysis of snow in regions in which there are a range of snowpack conditions, or where a snowpack undergoes rapid metamorphosis. However, analysis of both polarizations may reveal information concerning the structure of a snowpack.